Aqueous coating compositions containing a latex having chain-pendant amine functional groups have been known from U.S. Pat. No. 5,922,398. The amine-functionalised latices of this document may be prepared in accordance with any of a number of methods, including but not limited to addition polymerisation of ethylenically unsaturated monomers containing amine-functionality; polymerisation of monomers which readily generate amines by hydrolysis; reactions of aziridines with carboxyl group-containing polymers; reactions of polymers containing an enolic carbonyl group, e.g., acetoacetoxyethyl methacrylate and diamines; reactions of amines with epoxy-containing polymers; and reactions of amines with polymers of vinyl benzyl chloride.
Cationic acrylic resins have also been known from EP 0 525 695 A1. These resins are based on copolymers made from esters of acrylic or methacrylic acids having secondary or tertiary amino groups, monoesters of dihydric alcohols and acrylic or methacrylic acids, esters of monohydric alcohols and acrylic or methacrylic acids, and optionally, further vinyl monomers such as styrene.
These resins are made by radically initiated polymerisation in the presence of epoxy-amine adducts. The mixtures thus obtained are used as cathodically depositable paint binders.
Corrosion resistance of coatings prepared with these resins as binders is worse than the corrosion resistance of coatings prepared from pure epoxy-amine adducts. On the other hand, acrylic polymers are notable for their low propensity to yellowing and also, chalking, particularly when exposed to light.
On the other hand, epoxy resins, i. e., resins derived from at least difunctional epoxide group-containing compounds, and particularly, epoxy-amine adducts, provide very good corrosion resistance to coatings prepared therefrom, but suffer from yellowing and light-induced degradation.